Preparation of catalysts



July 27, 1948. A. G. oBLAD ETAL PREPARATION OF CATALYSTS Filed July 12,1945 Patented July 27, 1948 PBEPARATIGN F CATALYSTS Alex G. Oblad andEdward B. Baedeker, Dallas,

Tex.,

alsignors, by mesne assignments. to Socony-Vacuum Oil Company,Incorporated, New York, N. Y., a corporation of New York ApplicationJuly 12, 1945, Serlal N0. 604,714

This invention relates to improved catalysts and the preparationthereof. More particularly. this invention relates to an improved methodfor preparing supported aluminum chloride catalyst for use in suchhydrocarbon conversion processes as alkylation, isomerization,polymerisation, cracking and the like. Speciilcally. this inventionrelates to an improved method of impregnating highly porous catalystsupports such as alumina gel or silica gel with aluminum chloride in amanner such that the catalytic elciency of said supports and of thesupported aluminum chloride is not reduced by non-uniformcoating of saidsupports with the aluminum chloride.

Supported aluminum chloride is widely used as a catalyst in catalyticconversion processes particularly in the renning and conversion ofpetroleum hydrocarbons. Various methods have been proposed for preparingand regenerating the supported catalyst. Thus. it has been proposed tomechanically mix the aluminum chloride and Vthe support and then to pillthe mixture or the mixture may be heated and subjected to pressure toobtain more intimate contact of the support with the catalyst. Anothermethod suggested is to volatilize the aluminum chloride and adsorb thevapors on the support. Another method which has been proposed is todissolve aluminum chloride in the liquid hydrocarbon feed to the processfrom which solution the aluminum chloride is removed and adsorbed by theporous support. While this procedure is an excellent method fordepositing the more soluble aluminum bromide on the porous support, thelimited solubility of aluminum chloride in hydrocarbons and hydrocarbonmixtures makes the method less adaptable for etllciently preparing asupported aluminum chloride catalyst containing relatlvely large amountsof aluminum chloride.

An object of our invention is to prepare a unli'ormly impregnated poroussolid material with aluminum chloride. Another object of our inventionis to regenerate a partially spent supported aluminum chloridecatalytically active material for use in such hydrocarbon conversionprocesses as isomerization, alkylation and cracking. A further object ofour invention is to Drepare a highly active form of poroussolid-supported aluminum chloride catalyst the penetration of the poresof said support having aluminum chloride distributed uniformlytherethrough. A still further object of the invention is to provide amethod for applying to a porous 4 Claims. (Cl. 252-251) solid carrier auniformly distributed Friedel- Crafts type catalyst comprising aluminumchloride with or without controlled amounts of intimately associatedaluminum bromide in said catalyst. An additional object of our inventionis to provide an improved method and means for combining our poroussolid or gel type supported Friedel-Crafts type catalyst with promotersfor such hydrocarbon conversion processes as isomerization andalkylation. These and other objects will be apparent as the detaileddescription of our invention proceeds.

In the preferred embodiment of our invention we first impregnate themoisture-free porous solid or gel type support with aluminum bromide bycontacting said support with a solution of aluminum bromide in asuitable solvent such as normal butane. normal pentane or normal hexaneor mixtures of these at a temperature preferably below 150 F. and atpressures sufilcient to maintain the solution in liquid phase. We preferto use normal butane as the solvent and to carry out the aluminumbromide adsorption at temperatures within the range of from F. to about150 F. Thus, at 100 F. the solubility of aluminum bromide is about 40parts by weight of aluminum bromide per 100 parts by weight of solutionin the above solvents. 0n the other hand the solubility of aluminumchloride in these solvents at 100 F. is less that 0.002 part per 100parts of solution and even at 200 F. the solubility of aluminum chlorideis less than one part per 100 parts of solution While aluminum bromideis miscible with these solvents in all proportions at 200 F. Hence, weutilize the more soluble aluminum bromide in the solution contactingstep of our process. When the desired amount of aluminum bromide hasbeen adsorbed by the support as determined by direct analysis of theimpregnated support or indirectly by analysis of the aluminum bromidedepleted solution, the solvent is removed and the impregnated support iscontacted with free chlorine and/or hydrogen chloride either in the gasphase or preferably by a hydrocarbon solution of chlorine or hydrogenchloride the aluminum bromide impregnated carrier being converted insitu to aluminum chloride impregnated carrier. This chlorinesubstitution step of our process is preferably carried out at relativelylow temperatures within the range of from about 50 F. to about F. inorder to minimize the reaction of the dissolved chlorine with thehydrocarbon. Free displaced bromine passes into the hydrocarbon solvent.A small amount of hydrogen bromide is also formed and these twoproducts. both ot which are activators for the aluminum bromidecatalyst. are also adsorbed to some extent on the carrier support, thusfurnishing activators in situ for the supported catalyst. In some casesthe bromine substitution step may be carried out at higher temperaturesin order to produce higher concentrations of halogen acids and alkylhalides in the hydrocarbon solvent. The chlorides may serve tosubstitute chlorine for bromine in the substitution step and thecorresponding bromides will react with metallic aluminum in thesucceeding step. described hereinbelow, to produce recycle aluminumbromide for the initial impregnation step.

The hydrocarbon solvent from the above described chlorine substitutionstep o! our precess which contains dissolved free bromine and which mayor may not contain appreciable amounts of hydrogen bromide and alkylbromide is contacted in a third reaction with activated metallicaluminum for the regeneration of aluminum bromide. This step oi' theprocess is carried out at temperatures within the range of about 80 F.to about 250 F. as described in copending Serial No. 681,164 entitledManufacture of aluminum bromide illed March 5. i945 (now U. S. PatentNo. 2,439,737, issued April 13, i944).

The accompanying drawing illustrates the process steps of the inventionin the form of a iiow diagram. The catalyst impregnation tower isillustrated as a continuous bed of porous solid packing but it is to beunderstood that other types of distribution of catalyst support in thereactor such as catalyst supported on separate trays is within the scopeoi our invention. Other auxiliary equipment such as heat exchangers,coolers, heaters, blowers. etc., the necessity for which will be readilyrecognized by those skilled in the art, have been omitted for the sakeof simplicity.

Referring to the dow diagram catalyst support such as activated aluminagel. silica gel. acid treated bauxite, or acid treated clay, such asacid treated bentonite, is heated in tower I to remove adsorbed water ina pretreatment step before impresnstins the support with aluminumbromide. Tower I consists oi' a reactor which may or may not be equippedwith internal heating or cooling coils for the control oi temperature ofthe specific reaction wherein the supported catalyst is used. Ii tower Iis so equipped. a heating iiuid such as ilue gas may be passed throughthe coils to produce the heat for drying the support. Flue gas is passedby means of blower 2 in line 3 through heat exchanger l where the gas isconditioned to a temperature within the range of from 400 F. to 750 F.The gas passes through line 5 to tower I and heat is transien'ed eitherindirectly through the coil walls or directly to the support by contactwith the same. The iiue gas passes from tower I through valved line l.When the support is substantially free o1' water, the temperature of theilue gas in line 5 is lowered to approximately atmospheric temperatureand the dow oi' gas is continued to lower the temperature of the supportto about 80 F. or 90" F. in preparation for the aluminum bromideimpregnation step.

Normal butano from line I containing dissolved aluminum bromide to theextent or from about to about 30 weight per cent is introduced to thesupport in tower l by means of pump III in line I I. The temperature ofthe solution as it enters tower I is within the range of from 60 F. toabout F. and tower I is maintained at a pressure within the .range oi'from atmospheric to 100 pounds per square inch gauge during theimpregnation step. As the solution passes upward through the toweraluminum bromide is extracted from the solution and adsorbed on theporous support and the solution. partially depleted with respect toaluminum bromide passes from tower I via valved line I2 to line I3. Wemay carry out the impregnation of the support by continuous circulationof the hydrocarbon by closing valve I l in line I5 and opening valve I8in line I'I which connects with line Il. When operating in this manner,the recycle butane stream, cooled by cooler Iii in line I1, is enrichedwith aluminum bromide introduced to line II via valved line l. The useof a continuously circulating stream of butane solution of aluminumbromide is particularly adaptable when it is desired to impregnate thesupport with relatively large amounts of aluminum chloride. If, on theother hand. only thin illms of aluminum chloride are desired on Lhesupport. the desired amount of aluminum bromide may be dissolved in thebutane and the solution is then retained in tower I in contact with thesupport until the aluminum bromide is adsorbed on the support afterwhich the aluminum bromide depleted solvent is removed from the systemvia line I5 or the butano, substantially depleted of aluminum bromide,may be passed through line I'I to line II for use in the next step ofthe process as described hereinbelow.

The aluminum bromide impregnation step of our process is followed by theconversion of the adsorbed aluminum bromide to aluminum chloride. To thestream of normal butane in line Ii, which may be fresh solvent orrecycled stock from line Il, is added free chlorine through line I9. Asthe solution of chlorine is passed upward through the aluminum bromideimpregnated support in tower I. the dissolved chlorine reacts with thesupported aluminum bromide to form in situ supported aluminum chloride.If desired, the hydrocarbon solution oi' chlorine may be divertedthrough line 20 which leads to manifold line 2| thereby introducing thesolution to the bed of support in tower I at a multiplicity of points inorder to obtain more uniform distribution of aluminum chloridethroughout the bed of support. During this operation a cooling medium iscirculated through internal heat exchange coils (not shown) in order toremove the exothermic heat oi the reaction of the chlorine with thealuminum bromide. The reaction is carried out at temperatures preferablybelow 75 F. in order to minimize reaction of the free chlorine in thefeed or free bromide reaction product with the hydrocarbon solvent. Thepressure maintained in tower I during this step of the process issufficlent to maintain the solution in the liquid phase and will bebelow 100 pounds per square inch gauge. With valve 22 in line I3 closedand valve 23 in line 24 open the hydrocarbon solvent containingdissolved bromine is passed by means of pump 25 to the bottom of reactor2E which is packed with aluminum metal preferably in the form of thinsheets or turnings of large surface area. This aluminum metal may beactuated with salts of mercury such as mercurio nitrate.

As the solution of bromine passes upward in contact with the aluminum inreactor 26, the bromine reacts with the aluminum to form aluminumbromide which dissolves in the hydrocarbon solvent. Considerable heat isgenerated and i: desired. this exothermic heat may be reanarcomovedbypermittingapartoitbesolventto vaporize us cooling the reactionmixture or a coolant y be passed through an internal heat exchanger (notshown) in reactor 2l. The temperature in reactor should be maintainedbelow about 250" F. and preferably within the range oi from about 125 F.to 150 F. The pressure should be sutllclent to maintain at least partialliquid phase conditions. Since aluminum bromide is soluble to the extentof about 80 grams per hundred grams oi butane lsolution at 150 F..considerable vaporization in reactor 2l can be tolerated and stillretain suillcient liquid solvent to carry the dissolved aluminum bromideto the succeeding separation step described below. I! the temperature inreactor 28 is too high. several side reactions may take place. The freebromine will react with a part of the normal butane to form butylbromide and hydrogen bromide. Isomerization of the normal butane toisobutane will also take place to some extent at temperatures aboveabout 125 F. and the isobutane in turn will be alkylated with the butylbromide to iorm octanes and more iree hydrogen bromide. Hence, in orderto avoid these side reactions it is desirable to operate reactor 2liwell below 250 F. and preferably below about 150 F.

The butane solution of the aluminum bromide formed in reactor 26 plusvaporized butane and any hydrogen bromide formed by the reaction oi thefree bromine with the butane solvent passes overhead through valve 21 inline 28 to condenser 28 where the butane vapor is condensed and theproduct passes thence by line 30 to fractionator 3| which is equippedwith reilux means 32 and heating means 33. Hydrogen bromide is takenoverhead from fractionator 3| through valved line 34 for use asactivator in an integrated aluminum halide catalysed isomerizationprocess or aluminum halide catalysed alkylation process or it may berecycled via lines I! and 24 to reactor 26 wherein the bromine contentof the hydrogen bromide may be recovered as aluminum bromide. The liquidproduct of iractionator 3| consisting oi' butane solvent and dissolvedaluminum bromide and a trace oi" alkyl bromide is passed by means ofpump 3B in line 21 to surge drum 38. From surge drum 38 the solution iswithdrawn through line 39 which connects with line 8, thus completingthe cyclic process.

One method of impregnating porous supports with aluminum halides hasseveral distinct advantages over previous methods known to the art. Forexample, it is possible by our process to superimpose on and in theporous support successive layers of aluminum chloride and aluminumbromide of any desired depth by adjusting the concentration of aluminumbromide in the impregnating solution and regulating the time of contactof the solution with the support. Thus, a relatively thick layer ofaluminum bromide may be impregnated on the support and only partialconversion of this layer to aluminum chloride can then be followed bythe deposition of a second layer of aluminum bromide. On the other handthe initially impregnated layer may consist of a relatively thin layerof aluminum bromide which can be completely converted to aluminumchloride and further impregnation with aluminum bromide to produce asupported combination of aluminum-chloride-aluminum bromide catalystwith the aluminum chloride in direct contact with the support. It iswell known that a mixture of these two halides of aluminum is morecatalytically active for the isomerization of normal butane and for thealkylation o! isobutane with oleiins than either halide alone. Ourcatalyst is also more active than other supported aluminum halidecatalysts due to adsorption oi hydrogen halide and halogen activators inthe impregnation step. Due to the use of a solution oi' aluminum bromidein the hydrocarbon such as normal butane much more uniform and completeimpregnation of the support can be made under less severe conditionsthan are required when using molten aluminum halides as impregnatingagents.

Our method ot ilrst impregnating the support with aluminum bromide andthen converting the bromide to the chloride by treatment oi' theimpregnated bromide with free chlorine may also be applied to thepreparation of supported aluminum chloride wherein the initialimpregnation is made with molten aluminum bromide which melts at a muchlower temperature than aluminum chloride. However. as stated hereinabove. more uniform and complete contact oi aluminum halides isobtainable by use oi' the hydrocarbon solution of the aluminum bromideas the impregnating agent. Likewise, porous supports may first beimpregnated with aluminum bromide vapors and the aluminum bromideimpregnated support can then be converted to porous solid supportedaluminum chloride by treatment with free chlorine and/or hydrogenchloride vapors.

Our improved method of impregnating catalytically active supports suchas alumina gel is of primary importance in ilxed bed catalyst systemswherein the impregnation oi the support represents a coordinated cycleto which the catalyst in the conversion reactor is subjected. However,supported aluminum chloride or supported mixtures of aluminum chlorideand aluminum bromide made by our method may be used in moving bed oriluid ow systems. Our invention is not limitedlto any particular type oiconversion system nor is it limited to the specific ow dlagram ashereinabove set forth since numerous modifications and alternativeprocedural steps and operating conditions will be apparent to thoseskilled in the art.

We claim:

l. A process for the manufacture of aluminum chloride impregnated poroussolid comprising the steps o! (1) contacting said solid with aparaillnic hydrocarbon solution of aluminum bromide for a sutllcienttime to adsorb aluminum bromide on said solid. (2) contacting thealuminum bromide adsorbed on the solid in step l with a parafdnichydrocarbon solution of suillcient chlorine for sumcient time to convertall oi said adsorbed aluminum bromide to adsorbed aluminum chloridewhereby said hydrocarbon solution oi chlorine is converted to ahydrocarbon solution or bromine, (3) passing the hydrocarbon solution oibromine from step 2 in contact with metallic aluminum to reformhydrocarbon dissolved aluminum bromide. (4) recycling the hydrocarbonsolution of aluminum bromide from step 3 to step l, and (5) recoveringaluminum chloride and aluminum bromide impregnated porous solid fromstep 2 oi the process.

2. The process of claim l wherein the porous solid is alumina gel.

3. The process of claim 1 wherein the hydrocarbon solvent for thealuminum bromide of step l and the hydrocarbon solvent for the chlorineoi step 2 is normal butane.

7 8 4. The moet: o! claim 1 wherein the norm u wm mmm. t merma suns umun o. om. Number Ilma DIM mwAnD n. mmm 2.851.517 Thomas June 19. 1944 52,942,939 Danforth Peb. 99, 1944 2.998.129 Veltman June 9. 19431,692,203 Iglo!! Nov. 90. 1929 me of this patent:

Certificate of Correction P01-,ent No. 2,446,100. July 27, 194s. ALEX G.oBLAD ET AL.

It is hereby certified that errors appear in the rnted speccation of theabove numbered patent requiring correction as follows: olumn 2, hue 30,for the words "less that read less than; column 3, line 28 for April 13,1944 read A 13, 1948; column 4, line 57 ,r for bromide read bromne;column 5, line 51, for ne method" read Our method; und that the saidLetters Patent should be reed wlth these correotions therein that theseme may conform to the record of the case in the Patent Oice;

Signed and sealed this 16th day of November, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommsaoner of Patents.

7 8 4. The moet: o! claim 1 wherein the norm u wm mmm. t merma suns umun o. om. Number Ilma DIM mwAnD n. mmm 2.851.517 Thomas June 19. 1944 52,942,939 Danforth Peb. 99, 1944 2.998.129 Veltman June 9. 19431,692,203 Iglo!! Nov. 90. 1929 me of this patent:

Certificate of Correction P01-,ent No. 2,446,100. July 27, 194s. ALEX G.oBLAD ET AL.

It is hereby certified that errors appear in the rnted speccation of theabove numbered patent requiring correction as follows: olumn 2, hue 30,for the words "less that read less than; column 3, line 28 for April 13,1944 read A 13, 1948; column 4, line 57 ,r for bromide read bromne;column 5, line 51, for ne method" read Our method; und that the saidLetters Patent should be reed wlth these correotions therein that theseme may conform to the record of the case in the Patent Oice;

Signed and sealed this 16th day of November, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommsaoner of Patents.

